Preheat oven to 350 degrees and lay cooked shells on a paper towel-lined baking sheet to dry.
Heat a saute pan and add olive oil to heat. Add in the minced onion and saute for 1-2 minutes. Do not brown.
Add in the ground meat, season with salt and pepper and lightly brown and break up as much as possible. Add in the minced garlic and cook another 2-3 minutes. Drain off any access grease. Add in the white wine and cook for 4-5 minutes or until the wine dries up almost completely.
Remove from the heat and let cool slightly. Add the meat mixture into the food processor with the breadcrumbs, cheese and parsley. Pulse until almost a paste.
Remove from the food processor, checking seasoning and make sure that the mixture is not hot and mix in the egg.
Layer the meat sauce in the bottom of a baking dish. Fill the shells generously, but not over filled.
Lay them on top of the sauce. Top with more meat sauce and the shredded mozzarella cheese.
Cover with plastic wrap and foil and bake for 45 minutes. Remove the cover and bake for an additional 15 minutes. Serve hot. ENJOY!